The Mystic Valley Regional Charter School, a suburban Boston charter in Malden, Massachusetts, is under fire for its dress-code policy prohibiting hair extensions and afros, rules that critics say are racially discriminatory.

Despite protests from civil rights groups, the state’s charter school association, and even the Bay State’s Democratic Attorney General Maura Healey, Mystic Valley—which voted Sunday to suspend its policies for the remainder of the academic year—defends its dress code as critical for promoting equity and student academic success.

The school's dress code sparked national attention earlier this month when parents of two African-American students at the school (15-year-old twins Deanna and Mya Cook) said their daughters received multiple detentions for wearing their hair in braids. They were also both barred from after-school sports, and Mya was banned from the junior prom. Though black students have worn hair extensions before, parents say Mystic Valley started cracking down on them in April.

Other Mystic Valley parents told The Boston Globe that their black children also received punishments for how they wore their hair. One mother said her daughter received detention for wearing braids. Then, when her daughter refused to remove them, she was suspended. Another mother told the Globe that an administrator called in her daughter, and 20 other girls, and asked them if they wore “fake” hair. Ten of those girls received detentions.

The school’s policy bans “drastic or unnatural hair colors or styles” and hairstyles that might be “distracting” to others. One example of an “unnatural” hair style is “hair more than two inches in thickness or height.” Black parents have noted that the school has taken no disciplinary action against white students who color their hair.

Mystic Valley originally defended its policy as necessary to minimize fashion expenses for enrolled students. “The specific prohibition of hair extensions, which are expensive and could serve as a differentiating factor between students from dissimilar socioeconomic backgrounds, is consistent with our desire to create an educational environment, one that celebrates all that students have in common and minimizes material differences and distractions,” Alexander Dan, the school’s interim director, said in a statement.

But civil rights advocates representing the Cook girls say the school’s explanation makes little sense. In a May 22 letter, the advocates—including the ACLU of Massachusetts, the National Women’s Law Center, and the Anti-Defamation League—wrote that “the assumption that wearing braids with extensions constitutes a marker of wealth is erroneous” because braids cost less than other hairstyles that are permissible under the school’s policy. Moreover, the civil rights groups note that Mystic Valley “imposes significant costs” on students who participate in athletic programs, potentially limiting those extracurricular activities only to students “who can pay to play.”

“The school charges kids to be in certain clubs, and you pay much more to be on an athletic team,” says Sarah Wunsch, the deputy legal director at the ACLU of Massachusetts, in an interview with The American Prospect. “So if they’re trying to even out any economic differences, it sure doesn’t look like it.”

The Boston Globe reported that braided styles using human or artificial hair can cost between $50 and $200 at Boston-area braiding salons. (Some individuals rely on family or friends to braid their hair at little to no charge.) The Cook girls have also worn chemically straightened hair styles; their parents said the price tag for both braids and straightened hair was about the same.

On May 15, the ACLU filed a complaint with the Massachusetts Department of Elementary and Secondary Education, saying that Mystic Valley’s hair policy “appears to be especially harmful to female students of color” and has been “enforced in a disparate manner against them.” This marks the second time the ACLU has filed a complaint against the charter school. In 2015, the civil liberties group contacted the state after Mystic Valley displayed signs that appeared to endorse a nearby Baptist church. The school quickly removed the signs.

Last Friday, even the head of the civil rights division in the state attorney general’s office informed the charter school that their hair and makeup policy “includes a number of prohibitions that are either unreasonably subjective or appear to effectively single out students of color.” The attorney general’s office is continuing to investigate the case, but called on Mystic Valley officials to “immediately cease enforcing or imposing discipline for violations” of their dress code as it pertains to hair extensions, afros, and shaved lines.

The Mystic Valley board of trustees met privately to discuss the matter over the weekend and ultimately voted to suspend the policies for the remainder of the school year. “The school will continue to work with the attorney general’s office to ensure that the uniform policy reflects our longstanding commitment to the rights of all our students,” said Dan, the school’s interim director. “Students who are either currently serving consequences or accruing them may immediately resume all before- and after-school activities.”

The Massachusetts Charter Public School Association praised the school officials’ decision but urged them to eliminate the policy altogether. “The Board took the right action to suspend its discriminatory policy, and now needs to rescind it permanently,” said Marc Kenen, the MCPSA’s executive director. “Charter schools aspire to develop cultural competence and achieve cultural proficiency. … Our students learn from each other’s differences.”

This week, the NAACP Legal Defense and Educational Fund (NAACP LDF), the ACLU of Massachusetts, and the Lawyers’ Committee for Civil Rights and Economic Justice announced they would be representing the Cook family and exploring legal action against Mystic Valley.

The civil rights groups criticized the charter school for failing to indicate how it would deal with the past punishments students received for dress-code violations, including whether the school would expunge students’ records of suspensions and detentions. They point to data from the state education department that shows black Mystic Valley students are nearly three times more likely to be suspended than white students, and for longer periods of time. And, according to the most recent U.S. Department of Education data, every girl suspended during the 2013–2014 school year was black.

In an interview with the Prospect, Rachel Kleinman, a senior counsel at NAACP LDF, said that the situation at Mystic Valley “goes way beyond just the braids ban” and reflects a national problem with aggressive disciplinary policies for minor infractions that disproportionally impact black students. While noting that laws vary from state to state, Kleinman says that “in general as we see a move towards so-called school choice, towards funding private schools and charter schools at the expense of traditional schools that are subject to greater accountability, we worry about [this] trend.”

Even though the school has suspended the policy, Mystic Valley officials have since doubled down on a defense of their dress code. In a May 21 letter to parents, the school claimed the code is “central to the success of our students” since it provides “commonality, structure, and equity to an ethnically and economically diverse student body while eliminating distractions caused by vast socio-economic differences and competition over fashion, style or materialism.” Mystic Valley officials also said they believe their dress code could withstand a legal challenge—though they do not wish to pursue one.

“I think they’re simply wrong about that,” says Wunsch of the ACLU of Massachusetts, in regards to Mystic Valley’s claim that their dress code is legally defensible.